Signal communication, such as wireless communication (e.g., radio frequency (RF), microwave, and satellite communication), generally utilizes well known signal filters for transmitting or receiving specific signal frequencies. A known problem is created once two or more filters are connected at a “common junction”, which is a last component before a shared antenna where simultaneous transmit and/or receive communications (e.g., multichannel communications) are to be performed. These complications arise from the receive and transmit filters affecting each other, altering their performance characteristics from those originally intended. This effect needs to be nullified to maintain separate channels/spectral purity (no leakage) to prevent overlap caused by one communication being stronger than another (e.g., a strong transmission overpowering a weak received signal). Additionally, if this affect is not nullified, damage can be done to various components in the transmit chain.
Passive multiplexers for signal filters may be designed such that components of filters are reconfigured to return to the characteristics desired when each original prototype filter was designed. That is, the effect above to be nullified by a passive multiplexer (e.g., a duplexer) allows for efficient signal transmission in both the transmit and receive modes of operation. Conventionally, modeling of filter multiplexers has been an ongoing challenge in the state of the art for RF/microwave filter researchers and manufacturers, with each using their own “in-house” special techniques. For example, to model a passive multiplexer, experts in the field (e.g., hardware filter manufacturers) have used labor-intensive and time-consuming physical testing (e.g., trial-and-error prototyping bench work), or inflexible and complex algorithms, typically with slow convergence or no convergence (i.e., not achieving a solution to nullify the effects of the common junction).